1. Field of the Invention
The present invention generally relates to powered devices (e.g., personal or laptop computers) in a Power over Ethernet (PoE) system, and more specifically to the separation of a switch and a power supply that are used in PoE systems in enterprise environments.
2. Related Art
Ethernet communications provide high speed data communications over a communications link between two communication nodes that operate according the IEEE 802 Ethernet Standard. The communications medium between the two nodes can be twisted pair wires for Ethernet, or other types of communications medium that are appropriate. Power over Ethernet (PoE) communication systems provide power and data communications over a common communications link. More specifically, a power source device (e.g., power source equipment (PSE)) connected to the physical layer of the first node of the communications link provides DC power (for example, 48 volts DC) to a powered device (PD) at the second node of the communications link. The DC power is transmitted simultaneously over the same communications medium with the high speed data from one node to the other node.
The PSE device is often a data switch. Typically, a PSE on a switch is called an endspan device. The switch is typically a networking bridge device with data ports that can additionally have routing capability. The switch could have as little as two data ports or as many as 400 or more data ports. It may have two or more rows of data ports, where a data port in an input row of data ports can be switched to any one of the data ports in an output row of data ports. Each data port can include a serial-to-parallel (i.e. SERDES) transceiver, and/or a PHY device, to support high speed serial data transport. Herein, data ports and their corresponding links can be interchangeably referred to as data channels, communication links, data links, etc, for ease of discussion.
Typical PD devices that utilize PoE include Internet Protocol (IP) phones (Voice over IP (VoIP) phones), wireless access points, etc. Personal computing devices, such as personal or laptop computers, are another example of PD devices. The power requirements of personal computing devices are significantly different, and often much higher than that of VoIP phones and wireless access points.
The powering of personal computing devices using PoE in an enterprise environment places a tremendous noise and power density burden on a switch PSE. An enterprise environment often uses a table top network switch for the switch PSE. Placement of a power supply for PoE within the table top network switch may require the table top network switch to dissipate a tremendous amount of heat. For example, in an enterprise environment with ten personal computing devices, such as laptop computers, and a network switch having 10-ports may require approximately 25 watts (25 W) of PoE per port to go to each laptop. More power may be required if one or more of the laptops are executing higher power applications, or powering a USB device, for example, or if trickle or regular charging is required. In addition, the network switch needs approximately 2 W per port just for the data portion of the networking. Thus, assuming 100% efficiency, the total power required for PoE and data communications is approximately 270 W. Inefficiencies within the enterprise environment, such as AC/DC conversion efficiency in the power supply to provide an example, may require the power supply to generate in excess of 270 W. In addition, the table top network switch is vulnerable to noise, such as switching noise radiated by the power supply, noise from fans include within the table top network switch to provide some examples. Conventional techniques, such a low pass filtering or electromagnetic interference enclosures to provide some examples, are available to reduce the noise generated by the power supply, but they are costly and require additional space that is at a premium. In addition, some enterprise environments have stringent noise and heat requirements whereby conventional techniques will not alleviate the heat or the noise generated by the power supply.
What is needed is a configuration for a table top network switch to efficiently dissipate heat and to reduce noise in a table top network switch.
The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number.